Is there a general principle of the timezone for timestamp fields in S/4HANA Cloud APIs?

Dear team,

In S/4HANA Cloud API design from architech level, is there a general principle of the timezone that applies to all timestamp fields?

Or is it still a case-by-case design?

Currently in Fiori APPs, there are still some time fields displaying UTC time, rather than user logon timezone time.

We learnt that SAP was internally planning to align all timezone displayed in Fiori APPs to user logon timezone next year in 2020.

Customer has concern that whether same issues might happen to S/4HANA Cloud APIs.

If so, implementation team might need to hard code the timezone conversion by different API.

BR

Fancy Zou